Prediction of Long-Term Minimum Concrete Temperature Using Climatic Variables (05-2135)**
Cesar Ivan Medina, Transtec Group, Inc.

Research findings have shown that concrete pavement temperature changes with depth. The most critical temperature changes take place at the top of the slab, where different factors combine causing high tensile stresses. A different condition has been observed for the mid-depth of the slab, where concrete temperature differentials are not too critical over time. This situation makes one think that although current concrete pavement thickness designs might be appropriate, reinforcement steel might be overdesigned. The Center for Transportation Research (CTR) at The University of Texas at Austin has performed extensive research in the area of concrete pavement evaluation. For design purposes, pavement instrumentations have shown that the effect of ambient temperature is more critical at the top of the pavement slab than at mid-depth and bottom locations. Field experiments have been conducted to monitor the evolution of concrete temperature for the short and long terms. A series of portland cement concrete pavement (PCCP) sections in various locations in Texas have been instrumented and temperature histories have been recorded using i-Buttons. This investigation intends to present the findings from this research and proposes a methodology that can be used for estimating the minimum concrete temperature for pavement design. The material presented here shows that concrete pavement temperature values are not as low as thought, which causes overdesigned steel contents. These ideas will provide valuable information and a positive step towards the standardization of the application of PCCP anywhere.